Comportamento do concreto reciclado confinado por materiais diversos

Abstract

The growing demand for sustainable alternatives in civil construction has driven the use of recycled aggregates derived from construction and demolition waste (CDW). However, the lower quality of these materials poses challenges to their application in compressed structural elements. In this context, external confinement emerges as a technique capable of compensating for the inherent limitations of Recycled Aggregate Concrete (RAC), enabling its use in loadbearing systems. Accordingly, this study investigates the behavior ofconventional and recycled concrete confined by steel tubes, Carbon Fiber Reinforced Polymer (CFRP), and Glass Fiber Reinforced Polymer (GFRP), aiming to understand the interaction between the concrete core and the confining material, as well as the effects of confinement type and level on overall performance. Experimental tests were carried out on stub columns, including strain analyses, failure mode assessment, and evaluation of different confinement configurations. A system Steel Tube Confined Recycled Concrete (STCRC) was examined by applying load exclusively to the recycled concrete core. Numerical models were developed in ABAQUS and calibrated using the experimental results. The results indicated that confinement significantly enhances the strength and ductility of RAC, reducing its performance gap relative to conventional concrete. Steel tubes provided active and stable confinement, although very thick walls reduced deformational compatibility. CFRP generated the highest strength gains but exhibited low ductility and brittle failure, whereas GFRP presented the best balance between strength and deformability. The numerical simulations reproduced experimental behavior and enabled the estimation of lateral pressures and confinement coefficients specific to each material. It is concluded that recycled concrete can achieve high structural performance when combined with appropriate confinement systems, with the type of confinement and the level of lateral stiffness being the key factors governing overall efficiency. The proposed models broaden the understanding of RAC confinement.